Optical access networks can be used to deliver high bandwidth communication services to the home or premise. One such optical access network is broadband fiber-to-the-premise (“FTTP”). FTTP has been regarded as the ultimate form of broadband access offering very high bandwidths to end-users. Today's FTTP systems are mostly offered through point-to-multipoint time division multiplexed (“TDM”) passive optical networks (“PONs”) or through point-to-point (“pt-2-pt”) optical Ethernets with individual home-run fibers.
TDM PONs use a 1:N power splitter (e.g., Ethernet-PON, Gigabit-PON, and 10G versions of these systems) at a remote node (“RN”) in the field to share a common transceiver at the central office (“CO”). TDM-PONs provide beneficial savings in the number of trunk fibers (between RN and CO) and optical transceiver counts at the CO. While saving patch panel space to terminate fibers, TDM-PONs do not scale well with bandwidth growth. Pt-2-pt optical networks provide very high bandwidths to end users, but do not scale well with optical fiber termination at the CO and fiber counts.
A wavelength division multiplexed (“WDM”) PON is another approach, which provides the benefit of fiber consolidation and pt-2-pt virtual links to end-users by assigning separate wavelengths between the CO and individual users. It can offer the benefits of both TDM-PON and pt-2-pt architectures. Traditional WDM-PON systems use a wavelength demultiplexer (as opposed to the power splitter used in TDM-PON) at the RN in the field to distribute a separate wavelength to each end-user in each direction.
In order to promote widespread adoption of FTTP broadband infrastructures, it is desirable to reduce the costs associated with fiber plant construction and ongoing operation and maintenance. One such expense is the detection and location of fiber faults (e.g., a fiber cut or breakage) that interrupt communication services. Such detection is necessary for repairing the broken fiber link and restoring the communication services. Techniques that can quickly and efficiently detect and locate these faults reduce the operation and maintenance expenses and further encourage adoption of FTTP communication services. In addition, these techniques shorten service outage time and improve user experiences.